Pinpoint Test F: The Tachometer Is Inoperative

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test F: The Tachometer Is Inoperative

Normal Operation

The PCM uses the Crankshaft Position (CKP) sensor to measure the engine rpm and sends the Instrument Cluster (IC) data over the High Speed Controller Area Network (HS-CAN) communication bus to command the tachometer gauge according to the data.

If the IC does not receive the engine rpm data from the PCM for 5 seconds or less, the IC defaults the tachometer to the last setting, based upon the last known good rpm message. If the IC does not receive the engine rpm data from the PCM for more than 5 seconds or if the data received is deemed invalid, the IC sets DTC U0100 in continuous memory and defaults the tachometer to 0 rpm.

NOTE: If DTC U0100 is set in the IC, other observable symptoms may be an inoperative speedometer, temperature gauge or odometer.

This pinpoint test is intended to diagnose the following:

- PCM
- IC



PINPOINT TEST F: THE TACHOMETER IS INOPERATIVE

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F1 CARRY OUT THE IC TACHOMETER ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC tachometer (TACH) active command and command the tachometer on. Observe the tachometer. The tachometer should start at 0 and move to 7,000 rpms.
- Does the tachometer sweep from 0 to 7,000 rpm when commanded on?

Yes
GO to F2.

No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.

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F2 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST


- Check for recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
- Are any PCM DTCs recorded?

Yes
REFER to Computers and Control Systems Information.

No
GO to F3.

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F3 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST


- Check for recorded IC DTCs from the self-test.
- Is DTC U0100 recorded?

Yes
GO to Pinpoint Test AU. Pinpoint Tests AU: DTC U0100

No
INSTALL a new PCM. REFER to Computers and Control Systems. TEST the system for normal operation.

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